In the development of reliable mechanistic models for prediction of solids flow behavior in silos or other solids handling and storage components and in systems such as coal handling and combustion facilities, knowledge of the solids flow characteristics can be gained from dynamic measurement of the top surface contour. The behavior of bulk materials stored in hoppers and silos and while being transferred into or out of storage in such vessels is of interest in optimizing the materials handling process. Further, the behavior of materials in dynamic processing systems such as combustors and fluidized beds is important to those involved in the design, development, or operation of such systems. Such materials behavior has been studied using probes to measure density, particle velocities, circulation patterns, and other parameters within the bed of materials. In addition to these parameters, mapping of the surface contour of the bed of materials under both static and dynamic conditions would be of considerable value. Knowledge of surface contour would be useful under static conditions for purposes such as materials inventory. Under dynamic conditions, control of the filling and emptying of hoppers, the fueling and ash removal processes for combustion/gasification vessels, and the monitoring and control of fluidized beds requires knowledge of the surface contour in order to optimize operating conditions.
In general contour mapping systems in use today fall in the category of radar, optical or acoustical. The use of radar systems is primarily for long range, such as airborne mapping of earth surfaces and does not provide the capability of short range resolution required in monitoring materials handling systems. Laser based optical systems have become effective with the introduction of high power, tunable lasers. However, such optical systems would not be useable in a dusty atmosphere which is normally associated with materials handling systems, especially coal handling systems.
Therefore, it is desirable to provide an acoustic based system for high resolution, short range, surface contour mapping. Conventional acoustic-based systems do not provide sufficient focusing of the acoustic beam to measure small differences in range over an area or object being surveyed. These systems do not have the capability of generating surface contour maps in real time while providing automatic focusing and density compensation. Real-time generation of accurate surface contour maps is necessary in order to gain knowledge of the dynamic behavior of bulk materials handling, especially in fluidized beds or gasifiers.
Accordingly, there is a need for an acoustic-based contour mapping system for real-time generation of surface contour maps of materials in confined containments from a fixed position at the top of the containment which is capable of autofocusing and density compensation.